JPS5949719B2 - Hybrid integrated circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hybrid integrated circuit device having a flip chip element, and more particularly to a hybrid integrated circuit device in which the reliability of the connecting portion of the flip chip element against the external environment is improved.

In hybrid integrated circuit devices, 1
Semiconductor chips with many transistors and diodes built into each chip may be used.

In this case, the problems are an increase in the cost of the bonding process due to the large number of connection terminals on the chip, an increase in failure rate due to defective bonding, a decrease in yield, and a decrease in reliability.How to solve these problems One of these methods is a bonding method using flip-chip devices, which is widely used. Flip-chip devices do not use lead wires such as wire leads or beam leads, but instead have connection terminals on a semiconductor chip that protrude from the chip surface (bumps), and insulate a conductor pattern that has a connection area at a corresponding position. Chips that are provided on a substrate and connected to each other by ultrasonic bonding or soldering are collectively called chips. However, since flip-chip devices have a structure in which the chip and the substrate are firmly connected through connection terminals and conductor patterns, it is difficult to absorb the difference in strain that occurs between the chip and the substrate, and it is difficult to absorb heat. There is a problem in terms of reliability against external environments that cause physical or mechanical distortion. For example, there is a difference in thermal expansion coefficient between the constituent material 51 of the semiconductor chip and the insulating substrate material Al2O3, and repeated strain occurs in the chip subjected to thermal cycles. Therefore, depending on the number of thermal cycles or temperature difference,
There is a risk that the connection will break due to fatigue, but in reality, the connection can be made strong enough to withstand such thermal strain, which is not a problem in practice. There are almost no such things. However, when handling a hybrid integrated circuit board having flip-chip elements directly as a mechanical component, for example, when using it for a recording head of a printer or facsimile machine, or a magnetic recording head of a video device, etc., When external forces and vibrations are applied, mechanical strain may be applied to the flip-chip portion, and depending on the magnitude of this strain, there is a sufficient risk that the connection portion of the flip-chip may be destroyed.

That is, mechanical strain is usually incomparably larger than thermal strain in both the speed and number of changes in strain, and the risk of fracture of the connection due to fatigue is greater than thermal strain. Conventionally, there have been few cases in which hybrid integrated circuit boards have been used directly as mechanical components, and therefore no measures have been considered to deal with the above-mentioned problem of the risk of flip-chip connections being destroyed due to mechanical strain. At present, there is a great demand for integrated circuit boards as the use of integrated circuit boards for mechanical parts is increasing.

This invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce the strain applied to the connections of flip-chip elements on an insulating substrate, thereby improving the reliability of the hybrid integrated circuit against the external environment to which the substrate is exposed. We are in the process of providing equipment.
This invention embrittles the connection area of the flip-chip element connection terminal of the conductor pattern on the insulated substrate that becomes a hybrid integrated circuit board and the peripheral area of the conductor in the vicinity, so that the conductor pattern is completely removed from the substrate in this area. By preventing the board from sticking to the board, the strain caused by the external environment is absorbed by the conductor in the flip-chip element connection area of the conductor pattern and its vicinity, as well as by the weakened part of the board, and the flip-chip This is to prevent the signal from being transmitted to the connection portion of the element.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

1 and 2 are a plan view and a sectional view showing the arrangement and connection state of one flip-chip element in a hybrid integrated circuit device according to the present invention.

In this figure, reference numeral 1 denotes an insulating substrate, for example a glazed substrate, on the surface of which are formed a conductor pattern 2, a connection area (land portion) 2a corresponding to the connection terminal of the flip-chip element, and a lead pattern 2b connected to this. ing. This conductor pattern 2 is made of Cr-Au on the substrate 1.
It is made by depositing a film and photoetching it. Land portion 2a and drawer lead pattern 2b
2μ of Ni, 5μ of Cu, and 15μ of solder are layered and adhered to a part of the plate by plating. Here, in the glass layer 5 on the surface of the substrate 1, the peripheral portion of the land portion 2a of the conductor pattern 2 and the extraction lead pattern 2b near the land portion 2a (the area surrounded by the dashed line in FIG. 1) becomes brittle. has been done. In FIG. 2, 5a indicates the embrittled glass layer portion. This partial embrittlement of the substrate 1 is shown except for the exposed portion of the glass layer in the area surrounded by the dashed line in FIG. Board 1
This is achieved by treating the substrate 1 with hydrofluoric acid while masked. A flip-chip element 3, for example a flip-chip diode array, was prepared, and its connection terminal (bump) 4 was connected to the land portion 2b of the conductor pattern 2 by face-down bonding. On the other hand, for comparison, a flip-chip element was connected under the same conditions to a conductor pattern formed in the same manner on a substrate that had not been subjected to hydrofluoric acid treatment.

In order to investigate the reliability of the connection part of the flip-chip element 3 against externally applied strain for the two types of samples obtained in this way, repeated strain was applied to the insulating substrate of each sample, and the open incidence rate of the diode was compared. did. As a result, in the samples whose substrates were not treated with hydrofluoric acid, the diode open occurrence rate reached over 50%, whereas in the samples whose substrates were treated with hydrofluoric acid, it was less than 10%. In addition, when we conducted an experiment in which we forcibly peeled a flip-chip device from a substrate, we found that in samples where the substrate was not treated with hydrofluoric acid, the connection terminals of the flip-chip device were cut at the root, whereas In the treated sample, the glaze layer below the land also peeled off.

Furthermore, when the substrate was replaced with a transparent glass substrate and the same process as in the previous example was performed, observation from the back side of the substrate revealed that in the areas treated with hydrofluoric acid, the glaze layer was formed along the land portions and the lines of the lead pattern. A crack was observed.

In this case, there were no particularly noticeable signs of fatigue such as cracks in the conductor pattern portion corresponding to the portion of the substrate treated with hydrofluoric acid. As is clear from the above embodiments, in the hybrid integrated circuit device according to the present invention, the thermal and mechanical strain generated in the substrate is applied to the flip-chip element connection area of the conductor pattern, the conductor in its vicinity, and even the embrittled portion of the substrate. , so it is not directly transmitted to the connections of the flip-chip device.

Therefore, even when using a hybrid integrated circuit board equipped with a large number of flip-chip elements, there is no risk that the connection parts will be destroyed by thermal or mechanical strain on the board, and its reliability is significantly improved. improves. Of course, it is effective against thermal distortion not only from external heat but also from heat generated by the flip-chip element itself (semiconductor in most cases). In addition, the embrittlement treatment of the substrate surface is
The conductive pattern is not removed by removing the surface of the substrate, but the embrittled layer also functions as a support for the conductive pattern. For example, when bonding a flip-chip device, force is naturally applied to the conductor pattern, but even if the conductor pattern is thin such as a vapor-deposited film or a sputtered film, it is supported by the embrittled layer underneath and is susceptible to breakage. Prevented. In the above embodiments, an example was described in which a conductor pattern was formed using a thin film technique on a glazed substrate, but the material of the insulating substrate and the technique for forming the conductor pattern are not limited thereto.

[Brief explanation of drawings]

FIG. 1 is a plan view showing essential parts of a hybrid integrated circuit device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line XX' in FIG. 1. 1...Insulating substrate, 2...Conductor pattern, 3...Flip chip element, 4...
·Connecting terminal.

Claims (1)

[Claims] 1. In a hybrid integrated circuit device in which a flip chip element having a plurality of protruding connection terminals is connected to a conductor pattern on an insulating substrate having a connection region in a portion corresponding to the connection terminal, the conductor pattern of the insulating substrate 1. A hybrid integrated circuit device characterized in that a connection region and a peripheral portion of a conductor in the vicinity thereof are made brittle.